Hydraulic lift



June 7, 1938. E. R. BARRETT 7 2,119,632,

HYDRAULIC LIFT Filed March 30, 1936 3 Sheets-Sheet l I N V E N TOR Eda4rd )2 Barrel?- A TTORNEYS.

June 7, 1938.

E. R. BARRETT HYDRAULIC LIFT Filed March 30, 1936- 3 Sheets-Sheet 2Edward 72 23417622.

ATTORNEYS.

June 7, 1938. E. R. BARRETT HYDRAULIC LIFT Filed March 30, ;956

5 Sheets-Sheet 3 l N V EN TOR ZTJ I'J )2 154271222.

A TTORNEYS.

Patented June 7, 1938 PATENT OFFICE.

HYDRAULIC LIFT Edward R. Barrett, Detroit, Mich., assignor to Gar WoodIndustries, Inc., a corporation of Michigan Application March 30, 1936,Serial No. '71,598

9 Claims.

This invention relates generally to hydraulic lifts. More particularlyit relates to a hydraulic lift mechanism adapted particularly forutilization in the actuation of pivotally mounted dump bodies forautomotive trucks.

It is a general object of the present invention to provide a novel andimproved type of hydraulic lift mechanism which is particularly simplein construction, effective in operation, and adaptable to many andvarious types of installation.

The present application contemplates a construction which includes arotary pump adapted to be connected to and operated by a conventionalrotary power take-oft mechanism from the vehicle on which the particularhydraulic lift mechanism is mounted. Means are provided for simplyadjusting the mechanism to operate on vehicles which have power take-offmechanisms on either the right or left-hand side thereof and,

in addition, means are provided for adapting the improved lift mechanismto a power take-01f which runs in either clockwise or counter-clockwisedirection. The present invention contemplates the provision of a headstructure embodying the pump and control mechanism which may beremovably securred to the cylinder portion of the hydraulic lift andwhich may be connected in any one of a plurality of positions thereon inorder to adjust the mechanism to cooperate with so the particular typeof power take-ofi mechanism with which the vehicle is equipped.

Still further, the present invention contemplates the provision of ahydraulic lift mechanism in which no auxiliary fluid reservoir isrequired and one in which the lifting cylinder is utilized for thepurpose of storing surplus fluid,

thus providing acompletely closed system.

It is an object of the present invention .to provide a hydraulic liftmechanism in which effective means are included for controlling the rateof lift and further means are provided for bypassing fluid when maximumlift is obtained in order to prevent the development of prohibitivelyhigh pressures within the lifting cylinder. -15 It is a still furtherobject of the present invention 'to provide a hydraulic liftconstruction in which a poppet type of valve is utilized for the purposeof controlling communication between the interior of the liftingcylinder and the pump 50 in order to effectively seal the same when apredetermined degree of lift is obtained.

Yet another object of the present invention consists in the provision ofa rotary type of control valve which serves to regulate the rate at :5which fluid is by-passed around the pumping mechanism and which rotaryvalve is provided with cam means for actuating the poppet valve whichserves to control the passage of fluid into and out of the liftingcylinder.

Many other and further objects and advantages of the present inventionwill become clearly apparent from the following specification whenconsidered in connection with the accompanying drawings forming a partthereof.

In the drawings:

Figure 1 is a fragmentary, side elevational view, with parts brokenaway, illustrating'the improved hydraulic lift mechanism mounted foractuating a dump body of a truck;

Fig. 2 is an enlarged, sectional view, taken substantially on the line2-2 of Fig. 1, illustrating in detail the internal construction of theimproved cylinder head and control mechanism;

Fig. 3 is an end elevational view of the cylinder head, showing the samemounted upon the cylinder and the manner in which the same is securedthereto;

Fig. 4 is a longitudinal, sectional view, taken substantially on theline 4-4 of Fig. 2, illustrating in further detail the interiorconstruction of the cylinder and the cylinder head, showing the valvecontrolling mechanism;

Fig. 5 is a transverse, sectional view, taken substantially on the line5-5 of Fig. 2, illustrating in detail the construction and arrangementof the ports providing communication between the improved cylinder headand the cylinder;

Fig. 6 is a sectional view, taken substantially on the line 6--6 of Fig.2, illustrating in detail the pump mechanism and the ports communicatingtherewith; and

Fig. 7 is a transverse, sectional view, taken substantially on the line1-1 of Fig. 6, illustrating in detail the construction of the rotarycontrol valve for by-passing fluid around the pump.

Upon referring more particularly to the accompanying drawings, it willbe clear that the specific embodiment of the invention illustratedtherein is merely illustrative of the generic inv'entive conceptpresented in this application, and that many modifications,substitutions and changes therefrom may be made without depart-' ingfrom the generic scope of the invention set forth in this application.

One form of the novel hydraulic lift mechanism disclosed in thisapplication is illustrated .in Fig. 1 as utilized for the purpose ofactuating a dump body of an automotive truck. As is conventional inconstructions of this general character, the dump body is supported upona framework III which may be made up of a plurality of elements ofchannel section, as shown. This framework adjacent the rear end thereofis provided with suitable downwardly extending projections II whichprovide a pivotal connection with a transversely extending shaft l2mounted in the main frame of the vehicle l3. It will be appreciated thatthis construction is substantially conventional and provides a pivotalmounting for the. framework supporting the dump body with respect to theframe of the vehicle proper.

The improved hydraulic lift mechanism, hereinafter described in detail,is of substantially unitary construction and includes a cylinder I5which is preferably permanently mounted in a cylinder head l6 describedin detail below. The

cylinder head l6 at each of its lateral sides is provided with coaxiallydisposed trunnions I! which may be mounted in suitable bearings carriedbythe framework l3 of the vehicle. It will be appreciated that thepivotal mounting of this cylinder head permits a pivotal movement of thecylinder [5 as a whole about the axis of the trunnions I1 and,consequently, the cylinder will move about this axis as the dump body istilted, as will hereinafter be more clearly seen.

Interiorly the cylinder I5 is provided with a piston which may have theperipheral surface thereof circumferentially grooved to receive suitablepiston rings 2| in order, to effect a tight seal with the wall of thecylinder with which it cooperates. The piston 20 has a concave forwardface 22, the purpose and function of which will hereinafter become moreclear. A piston rod 23 is permanently and rigidly secured to the piston20 by means of a suitable axially extending portion 24 which isexternally threaded to receive a nut 25 which locks the piston 20 firmlyinposition on the end of the piston rod 23.

The opposite end of the cylinder I5 is closed by a suitable cap member25 which is preferably permanently secured thereto and in its centralportion is provided with a packing gland 26 of conventional constructionwhich serves to receive and permit the passage of the piston rod 23. Byreference to Fig. 1, it will be appreciated that the piston rod 23extends outwardly from. the cylinder and is pivotally connected by meansof a suitable bearing 21 at its outer end to the framework whichsupports the pivotally mounted dump body. Interiorly, the cylinder I5 isprovided with a conical compression coil spring 28 which serves tocushion the outward movement of the piston in thecylinder and alsoserves to aid in returning the piston to normal position when fluidpressure within the forward portion of the cylinder is relieved, ashereinafter described in detail.

The cylinder head I6 is preferably formed from a single integral castingand provides a wall 30 which serves to substantially close the end ofthe cylinder 23. As is clearly seen by reference to Fig. 2, this wall 30is located substantially inside of the cylinder I5 and fits into thehollow face 22 of the piston when the piston is disposed at the innerend of the cylinder. This casting I6 is formed to provide a recess insubstantially the central portion thereof which serves to providespacefor mounting a poppet valve, hereinafter described in detail. This space3| is defined by a surrounding wall 32 which terminates in the plane ofthe face of the cylinder head I6.

As will be seen by reference to Fig. 4, a suitable bore or duct 33provides communication between this space 3| and the interior of thecylinder l5. The parts above described are all integrally formed as apart of the casting l6 forming the cylinder head and it will be notedthat the-various parts are so constructed and arranged that a duct 35 isformed which provides communication between spaces 36 on opposite sidesof the valve receiving structure 32.

The cylinder I5 is provided adjacent its outer end with an aperture 46which permits the escape of fluid from within the cylinder into afitting 4| and pipe 4| which connects with the space 36 in the cylinderhead. The function and operation of the improved pumping head have beendescribed in detail.

By reference to the drawings, it will be noted that the axial face ofthe cylinder head I6 is a smooth plane surface and lies in the sameplane as the valve housing 3| in the central portion thereof. It willfurther be clear that the spaces 36 which provide parts. for the feedingof fluid to and from the cylinder head, are symmetrically disposed inthe cylinder head construction as a whole and, by reference to Fig. 5,it will be seen that a plurality of internally threaded apertured holes42 are drilled in .the cylinder head to receive bolts 43 for thesecurement of the improved pumping head in position and it will beappreciated that these holes are symmetrically disposed with respect tothe cylinder head as a whole.

The improved pumping head includes a valve seat plate member 50 whichhas an outer configuration substantially the same as the axial face ofthe cylinder head 16 and has a smooth, plane surface adapted to matetherewith in sealing engagement. This valve seat plate is provided inits central portion with an opening 5| which is ground to provide aconical seat for a conventional type of poppet valve 52 mounted in thepump housing hereinafter described in detail.

The recess 3 I which is formed in the cylinder head constructiondescribed above, is provided with an annular projection 53 in thecentral portion thereof which serves to position a compression coilspring 54 bearing against the face of the valve 52 to maintain thisvalve normally in engagement with its valve seat. The valve 52 isprovided with a cylindrical projection 55 thereon which cooperates withthe cylindrical recess 56 formed by this annular projection 53 toprovide a guide which serves to align the valve 52 with its seat.

The valve seat member 56 is provided with a relatively large aperture 60which communicates with one of the spaces 36 in the cylinder head l6 andpreferably registers therewith.

seat plate 50 are retained in unitary relation with the cylinder head l6by means of the six symmetrically disposed bolts 43 which are threadablyreceived in the apertures 42 in the cylinder head;

The central portion of this housing 65 is pro vided with a cylindricalbore 66 adapted to receive the stem of the valve 52 and it will beappreciated that this bore'is coaxially disposed with the valve seat 5|in the valve seat plate 50. The valve seat plate 50 and housing areretained in their predetermined relative positions by means of aplurality of pins 61 which seat in complemental recesses in the twomembers.

On one side of the central portion thereof, this pump housing structureis provided with a recess 68, the open face of which preferablyregisters with the opening 60 in the valve seat plate and consequentlyprovides together therewith and with the space 36 a substantially openreservoir which communicates through the passageway 35 with the space 36on the opposite side of the cylinder head.

A pair of axially disposed intersecting cylindrical bores are providedin the pump housin structure on the opposite side thereof from the sideon which the recess 68 is located. and these bores 10 and 1| serve tohouse intermeshin gears 12 and I3, respectively. which togetherconstitute a pump for feeding oil to the cylinder in the mannerhereinafter described in detail. The gears 12 and 13 are preferablykeyed to shafts 14 and 15. respectively. which shafts extend throughsuitab e glands to the exterior of the housing and each is provided withmeans for attaching a shaft I1 from a suitable power take-off such as isconventionally provided in vehicles of this kind.

Inasmuch as, in conventional constructions of this character. powertake-off drives are generally not reversible, it will be apparent thatthe pump may be driven in the desired direction by connecting the powertake-off shaft 11 to whichever of the shafts I4 or I5 is desired. thusproducing the desired direction of rotation for th s gear pump.

The outer surface of the valve seat plate 5 s deformed to provide a portcommunicatin with the aperture 5| which. as has been described above. isclosed by means of the poppet valve 52, and it will be seen that thisport communicates with the outlet side of the gear pump. As has beenexplained above. the valve seat plate so is provided with an aperture 6|which serves to admit fluid from the space 86 to the inlet side of thegear pump.

The pump housing structure as a whole is provided with a transverselyextending bore 80 of substantial size. which provides communicationbetween the recess 68 and the outlet side of the gear pump. It will beclearly seen by reference to Fi 2 that this transverse bore 80 extendspast the path and intersects the cylindrical bore 66 which serves toreceive the stem of the valve 5 A hollow rotary valve element iii ofcylindri al configuration is mounted in this bore no and the outer endof the bore is preferably clos d b means of a suitable annular ca member82 which. n the axial central portion thereof. is prov d w th a packinggland 83. throu h hich passes the n tuating shaft 84 of the valve 8 Asuitable crank arm 86 is secured to this actuatin shaft 84 and to theouter end of the crank arm is pivotaily secured a fitting 81 whichserves to provide means for connecting a forwardly extending actuatingrod 88 which may be manipulated in any convenient manner from thedrivers compartment'of the vehicle with which the apparatus isassociated.

The cylindrical bore 80 has a suitable aperture 98 in the wall thereofwhich provides communication with the recess 68. The valve element 8|.

is hollow, as has been described above, and is open at its inner axialend. The wall of this valve element 8| is provided with an aperture 9|which, by rotation of the valve element, may be brought into registrywith the opening 90 in the wall of the cylindrical bore 80, consequentlyproviding communication between the recess 68 through the apertures 90and 9| and the hollow interior of the valve with the outlet side of .thep mp- The portion of this rotary valve element 80 which lies adjacentthe end of the valve 52 is of reduced diameter and is preformed on itsexterior surface to provide a symmetrical structure having cam faces 94and 95 on the opposite sides thereof. Due to the fact that the mainportion of the valve element 8| is of cylindrical configuration andclosely fits within the bore 80,it will be appreciated that as the valveelement is rotated, it will always rotate around a predetermined axis.The inner end of the stem of the valve 52 is preferably recessed toprovide a concave surface adapted to seat a ball 96 which is adapted tobe engaged by the cam surface of the rotary valve element 8|.

From the foregoing, it will be apparent that, with substantially minorchanges, the hydraulic lift mechanism described herein is fairly easilyconverted to be utilized with a vehicle which has the power take-offmechanism on either the right or left-hand side thereof and theconstruction of the device is such that it is immaterial whether thepower take-off mechanism runs in clockwise or counter-clockwisedirection, inasmuch as the power take-off mechanism can be connected toeither one or the other of the shafts of the gear pump, as may bedesired, in order that the gear pump will always be operated in the samedirection. Further, it is believed clear from the foregoing thatrelatively simple means are provided for connecting the control'rod tothe device irrespective of whether it is arranged for a right orleft-hand power take-ofl'.

The operation of the apparatus is substantially as follows. After thedevice has been completely assembled. as is illustrated in Fig. 1, theentire system is filled with oil. When the dump body is in normalposition upon the chassis of the vehicle, it will be appreciated thatthe piston 20 is seated in the inner end of the cylinder. The operatingrod 88, by means of suitable control mechanism in the cab of thevehicle, is moved forward and starts bringing the aperture 9| in thehollow valve into registry with the port 90. The power take-01fmechanism is now engaged. which starts rotation of the gears 12 and 13of the gear pump. which gears will draw oil in through the inlet port 6|and force this oil into the outlet side of the pump where this oil willpass through the axial end of the hollow valve element 8| out throughthe ports 9| and 90 into the reservoir or recess 68. From this po nt,the o l may pass into the space 36 through the duct 35 and back throughthe intake port 6| of the and consequently the pump will build upsubstantial pressure at the outlet side thereof, which pressure will beexerted on the under-side of the poppet valve 52, thus opening thisvalve. The opening of the valve 52, as a result of this increasedpressure, will permit the flow of oil into the space 3|, thence throughthe port 33, into the cylinder IS on the inside of the piston 20. Asthis pressure increases, it will be sufliciently great to force thepiston 20 outward in the cylinder 5, consequently effecting a tilting ofthe dump body framework Ill. The cam surfaces 94 and 95 are preferablyso constructed'and arranged that considerable rotation of the valveelement 8| may take place without causing a positive actuatingengagement of these cam surfaces with the ball 98. However, it will beappreciated that when the valve element 8| is rotated in a clockwisedirection, as viewed in Fig. 4, the cam face 94 of the valve element 8|will engage the ball 96 and serve to raise the valve 52 off its feet. Aswill hereinafter be more clearly apparent, the

'rotary valve element 8| may be rotated to an extent which will bringthe opening 9| thereof into partial registry with the opening 90 priorto any eflcctive engagement of the cam surface 84 with the ball 96.

The conduit 4|, described above, communicates with a suitable port inthe-cylinder head, providing communication between this conduit and thespace 36 in the cylinder head. Thus, it will be seen that at all timesconstant communication is maintained between the space 36 and theinterior of the cylinder on the outer side of the piston 2|). Thisportion of the system there'- fore constitutes a reservoir for the fluidwhich is not actually in use in the device.

Due to the symmetrical disposition of the bolts 43 and the symmetricaldisposition of the holes in the valve plate member and through thepumphousing through whichthese bolts pass, it will be appreciated that inthe event the power takeoff on the particular vehicle with which thehydraulic lift of the present invention is used, is located on either ofthe sides of the vehicle, the pump may be assembled to operate incooperation therewith. In case this is desired, it will be appreciatedthat the bolts 43 may be all removed and the pump housing and valvehousing swung through 180 degrees and again be bolted in position uponthe cylinder head. Such a reorganization of parts will position theshafts 14 and- 75 which serve to provide means for driving the gear pumpon the opposite side of the vehicle from that in which they are shown inthe embodiment of the invention illustrated in the drawings.

When the pump housing head is swung through .180 degrees, it isnecessary to disconnect the crank arm '86 from the shaft 84 to which itis secured, and reconnect it in a new position diametrically opposite tothat in which it originally was positioned. The movement of this crankarm will cause it to assume a position when the pump head is reversedsubstantially the same as it occupied when the pump head was in itsoriginal position, except that it will be disposed upon the oppositeside of the device.

It will be appreciated that if the port 9| is not completely closed, acertain amount of the oil will be by-passed around the pump andconsequently the amount of oil pumped through the opening and into thecylinder |5 may be accurately controlled and, consequently, the lift ofthe dump body may be as gradual as is desired. It will be appreciatedthat the piston 20 will move outward in the cylinder until the innerface of the piston passes the port 48, at which time it will beappreciated that oil pumped into the cylinder may pass through the port40 back through the conduit 4| into the space 36 adjacent the inlet sideof the pump, and, consequently, oil will be continually circulatedthrough the cylinder with-,

ly, the dump body will be retained at the maxi-- mum elevated position.The power take-off mechanism now may or may not be disconnected, as isdesired, and when it is desired to lower the dump body to its originalposition, .the push rod operating rod 88 pulled forwardly to a positionsuch that the cam surface 94 of the rotary valve element will engage theball 96 which, as has been explained above, is seated against the lowerend of the stem of the valve 52. This engagement of this cam surfacewith this ball will serve to raise the valve 52 from its seat and permita bleeding of fluid from the interior of the cylinder and consequentlypermit a gradual restoration of the dump body frame to its originalposition. Due to the gradual slope of the cam surface 94, it may beappreciated that this bleeding of fluid from the interior of thecylinder may be as gradual as is desired and may be discontinued at anytime in order that the dump body frame will be lowered as gradually oras rapidly as the operator sees fit.

From the above described construction, it will be clearly apparent that,as the dump body is raised, it may be conveniently stopped at any pointduring its upward path and it will be retained in exactly the desiredpredetermined position due to the tight seal effected by the poppetvalve 52. It Willbe appreciated that the construction described hereinprovides one in which a particularly effective and tight seal betweenthe cylinder and the pump is obtained by use of the poppet valve 52,consequently precluding the bleeding of oil from the interior of thecylinder except at times when such is desired.

It will be appreciated that the specific embodiment of the inventionherein illustrated and described is merely illustrative of the genericinventive concept presented in this application, and that many other andfurther modifications thereof, falling withinthe scope of the inventionas defined in the subjoined claims, will be apparent to those skilledin" the art.

What is claimed is:

1. A pumping head for hydraulic lifts including a pump, a poppet valvefor controlling communication between said pump and a hydrauliccylinder, a rotary control valve for by-passing fluid around said pumpand means on said rotary control valve for unseating said poppet valvewhen said control valve is opened.

2. A pumping head for hydraulic lifts including a pump, a poppet valvefor controlling communication between said pump and a hydrauliccylinder, a rotary control valve for by-passing fluid around said pumpand a cam associated with said rotary control valve for unseating saidpoppet valve when said control valve is opened.

3. A pumping head for hydraulic lifts including a pump, a poppet valvefor controlling communication between said pump and a hydrauliccylinder, a rotary control valve for by-passing fluid around said pumpand an integrally formed cam surfaced projection on said rotary valveserving to open said poppet valve when said control valve is opened.

4. A pumping head for hydraulic lifts including a pump, a poppet valvefor controlling communication between said pump and a hydrauliccylinder, a rotary valve for by-passing fluid around said pump and meanson said last mentioned valve for actuating said first mentioned valvewhen said last mentioned valve is opened.

5. In a hydraulic lift construction a cylinder and a cylinder head, apumping head secured thereto, a plate secured in position between saidpumping head and cylinder head, a valve seat in said plate, a valvecooperating with said seat and means in both said pumping head andcylinder head for guiding movement of said valve.

6. In a hydraulic lift construction, a cylinder and cylinder head, apumping head secured thereto, a plate secured in position between saidpumping head and said cylinder head, a valve seat in said plate, a valvecooperating with said seat, means in said pumping head for guiding saidvalve and means in said pumping head for actuating said valve.

'7. In a hydraulic lift construction, a cylinder and cylinder head, apumping head secured thereto, a plate secured in position between saidpumping head and said cylinder head, a valve seat in said plate, a valvecooperating with said seat, means in said pumping head for guiding saidvalve, and means including a rotary cam for actuating said valve.

8. In a hydraulic lift construction, a cylinder,

a cylinder head, a plate secured to said cylinder head, a pump housingsecured to said plate, said plate having a port therein serving toestablish communication between said pump housing and cylinder head, avalve for closing said port and means in both said cylinder head andpump housing for guiding said valve during movement thereof.

9. In a hydraulic lift construction, a cylinder,

a cylinder head, a plate secured to said cylinder

